题解

#include <iostream>
#include <vector>
#include <string>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> coefficients(n + 1);
    for (int i = 0; i <= n; ++i) {
        cin >> coefficients[i];
    }

    string result;
    bool isFirstTerm = true; // To manage signs for the first term

    for (int i = 0; i <= n; ++i) {
        int coeff = coefficients[i];
        int degree = n - i;

        if (coeff == 0) continue; // Skip zero terms

        // Handle sign
        if (!isFirstTerm) {
            if (coeff > 0) result += "+";
        } else {
            isFirstTerm = false;
        }

        // Add coefficient and variable/degree formatting
        if (degree == 0) {
            result += to_string(coeff); // Constant term
        } else if (degree == 1) {
            if (coeff == 1) result += "x";
            else if (coeff == -1) result += "-x";
            else result += to_string(coeff) + "x";
        } else {
            if (coeff == 1) result += "x^" + to_string(degree);
            else if (coeff == -1) result += "-x^" + to_string(degree);
            else result += to_string(coeff) + "x^" + to_string(degree);
        }
    }

    cout << result << endl;
    return 0;
}